cannot quite use openmp (PGI 6.0 Workstation)

Accelerated Computing HPC Compilers Legacy PGI Compilers
1

Hi there,

We got PGI workstation 6.0 installed on a 64-bit linux
SUSE LINUX Enterprise Server 9 (x86_64) - Kernel 2.6.5-7.193-smp (3).

I tested a code like below but just cannot have it show
thread_1 results. From the display, you can see that all
lines get thread_0 from OMP_get_thread_num().

Is “pgf90 -mp -L/usr/pgi/linux86-64/6.0/lib try6.f” correct for
the compiling? Was PGI fortran built properly?

Any opioion is very much appreciated.

Reggie


reggie@cluster:~/temp/pgf90>
reggie@cluster:~/temp/pgf90> cat try6.f
c use omp_lib
real r1
isum = 0.0
i_get_thread = OMP_get_num_threads()
write(,) ’ i_get_thread = ', i_get_thread

C$OMP PARALLEL DO
do k=1,6
ithread = OMP_get_thread_num()
write(,) 'ithread = ', ithread
enddo
C$OMP END PARALLEL DO
end
reggie@cluster:~/temp/pgf90>
reggie@cluster:~/temp/pgf90> pgf90 -mp -L/usr/pgi/linux86-64/6.0/lib try6.f -o
try6.out
reggie@cluster:~/temp/pgf90>
reggie@cluster:~/temp/pgf90> env|grep OMP_
OMP_NUM_THREADS=2
reggie@cluster:~/temp/pgf90>
reggie@cluster:~/temp/pgf90> try6.out
i_get_thread = 0
ithread = 0
ithread = 0
ithread = 0
ithread = 0
ithread = 0
ithread = 0

reggie@cluster:~/temp/pgf90>

2

additional info:

  1. The results are the same with pgf90 -mp try6.f -o try6f.out
  2. OMP_NUM_THREADS=2 has been defined prior to running try6f.out
    as is shown in the display
3

Hi Reggie,

You need to declare the OMP functions as INTEGER since the default type of variables beginning with “O” is REAL. Note that we added “omp_lib” to the 6.1 release.

Example:

% cat test.f
C        use omp_lib
        real r1
        integer OMP_get_num_threads, OMP_get_thread_num

        isum = 0.0
        i_get_thread = OMP_get_num_threads()
        write(*,*) ' i_get_thread = ', i_get_thread

C$OMP PARALLEL DO
        do k=1,6
                ithread = OMP_get_thread_num()
                write(*,*) 'ithread = ', ithread
        enddo
C$OMP END PARALLEL DO
        end
% pgf90 -mp -V6.0 test.f
% setenv OMP_NUM_THREADS 2
% a.out
  i_get_thread =             1
 ithread =             0
 ithread =             0
 ithread =             1
 ithread =             1
 ithread =             1
 ithread =             0

Hope this helps,
Mat

4

Hi mkcolg,

Thanks a lot for the tip! After declaring OMP_get_thread_num as inteter,
the code worked perfectly as your code indicated.

Best regards,

Reggie